The present invention relates to routing templates and more particularly to such templates that are intended for routing grooves in stair stringers or timbers.
A variety of templates have been developed for such a purpose. Typically, such a template includes a body plate which is placed upon the stringer and which contains mutually parallel slots that serve as guides for the a cutter. This permits the routing of grooves on the stringer for receiving the boards that will be the treads and risers.
The material prior art includes the following U.S. Pat. Nos.:
1,552,881; J. F. Rose PA1 1,615,213; R. L. Carter PA1 1,751,816; S. Hunter PA1 3,478,434; F. R. Catalano PA1 4,580,352; C. O. Wilson PA1 4,605,048; Swartout et al
Rose's device is designed to be used on a spindle molding machine, with the cutter operating on the underside of the stringer, with the template and guide pin on on top of the stringer. The stringer and template combination must be moved to achieve the routing action. The template must be reset for each cut and the template does not locate on the prior cut.
Carter's apparatus has a cumbersome reversing arrangement, and the positions for each template location have to be individually laid out: the template does not locate on the prior cut.
Hunter's device permits adjustability of the stair angle, but to make a left-hand stringer cut it is necessary to unclamp and reset the adjustable template plate. This device does not locate from the prior cut.
Swartout's design permits adjustment of angle and riser height, but depends on a fixed tread length. It does not locate a cut from a prior cut.
Wilson's and Catalano's devices, although described as templates, are used only for laying out the locations of the various grooves; they are not templates that guide the router cutter.
The prior art has not been wholly for the reasons indicated and other reasons.
It is an object of this invention to provide a routing template with automatic and accurate groove location by locating each cut from a preceding cut.
It is another object of this invention to provide a routing template that requires no adjustment or resetting to cut both a right hand and left hand stringer, thereby promoting accuracy and facilitating use.
It is another object of this invention to provide a routing template that does not require layout lines to be drawn on the stringer to denote groove locations.
It is yet another object of this invention to provide a routing template that has adjustments to accommodate variations in both riser and tread length dimensions.
Other objects and advantages of this invention will become apparent from the following description when taken in conjunction with the accompanying drawing.